Directions

1. Heat olive oil in a large skillet over medium heat.
2. Season beef with salt and pepper, to taste. Add beef to the skillet and cook until evenly browned, about 2-3 minutes; set aside.
3. Whisk together beef broth, tomato paste, Worcestershire, red wine vinegar and thyme in a 4-qt slow cooker; season with salt and pepper, to taste.
4. Stir in beef, onion and garlic. Cover and cook on low heat for 7-8 hours or high heat for 3-4 hours.
5. In a small bowl, whisk together cornstarch and 1/4 cup water.
6. Stir in mixture and mushrooms into the slow cooker. Cover and cook on high heat for an additional 30 minutes, or until the sauce has thickened.
7. Serve immediately, garnished with parsley, if desired.